Vessel sealing instrument with electrical cutting mechanism

ABSTRACT

An end effector assembly for use with an instrument for sealing vessels and cutting vessels includes a pair of opposing first and second jaw members which are movable relative to one another from a first spaced apart position to a second position for grasping tissue therebetween. Each jaw member includes a pair of spaced apart electrically conductive tissue contacting surfaces which each have an insulator disposed therebetween, the conductive surfaces are connected to an electrosurgical energy source. The first jaw member includes an electrically conductive cutting element disposed within the insulator which extends towards the second tissue contacting surface to create a gap therebetween. The cutting element is inactive during the sealing process while the two pairs of electrically conductive surfaces are activated to seal tissue. During the cutting process, the cutting element is energized to a first potential and at least one electrically conductive tissue contacting surface is energized to a different potential to effect a tissue cut through the tissue held between the jaw members along the already formed tissue seal.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of and is a continuation of U.S.application Ser. No. 10/932,612, filed on Sep. 2, 2004, entitled “VESSELSEALING INSTRUMENT WITH ELECTRICAL CUTTING MECHANISM”, now U.S. Pat. No.7,276,068, which claims the benefit of and is a continuation-in-part ofPCT application Ser. No. PCT/US03/28539 filed on Sep. 11, 2003 entitled“ELECTRODE ASSEMBLY FOR SEALING AND CUTTING TISSUE AND METHOD FORPERFORMING SAME” which claims the benefit of priority to U.S.Provisional Application Ser. No. 60/416,064 filed on Oct. 4, 2002entitled “ELECTRODE ASSEMBLY FOR SEALING AND CUTTING TISSUE AND METHODFOR PERFORMING SAME” the entire contents of each being incorporated byreference herein.

BACKGROUND

The present disclosure relates to a forceps used for both endoscopic andopen surgical procedures which includes an electrode assembly whichallows a user to selectively seal and/or cut tissue. More particularly,the present disclosure relates to a forceps which includes a first setof electrically conductive surfaces which applies a unique combinationof mechanical clamping pressure and electrosurgical energy toeffectively seal tissue and a second set of electrically conductivesurfaces which is selectively energizable to sever tissue between sealedtissue areas.

TECHNICAL FIELD

Open or endoscopic electrosurgical forceps utilize both mechanicalclamping action and electrical energy to effect hemostasis. Theelectrode of each opposing jaw member is charged to a different electricpotential such that when the jaw members grasp tissue, electrical energycan be selectively transferred through the tissue. A surgeon can eithercauterize, coagulate/desiccate and/or simply reduce or slow bleeding, bycontrolling the intensity, frequency and duration of the electrosurgicalenergy applied between the electrodes and through the tissue.

Certain surgical procedures require more than simply cauterizing tissueand rely on the combination of clamping pressure, electrosurgical energyand gap distance to “seal” tissue, vessels and certain vascular bundles.More particularly, vessel sealing or tissue sealing is arecently-developed technology which utilizes a unique combination ofradiofrequency energy, clamping pressure and precise control of gapdistance (i.e., distance between opposing jaw members when closed abouttissue) to effectively seal or fuse tissue between two opposing jawmembers or sealing plates. Vessel or tissue sealing is more than“cauterization” which involves the use of heat to destroy tissue (alsocalled “diathermy” or “electrodiathermy”). Vessel sealing is also morethan “coagulation” which is the process of desiccating tissue whereinthe tissue cells are ruptured and dried. “Vessel sealing” is defined asthe process of liquefying the collagen, elastin and ground substances inthe tissue so that the tissue reforms into a fused mass withsignificantly-reduced demarcation between the opposing tissuestructures.

To effectively seal tissue or vessels, especially thick tissue and largevessels, two predominant mechanical parameters must be accuratelycontrolled: 1) the pressure applied to the vessel; and 2) the gapdistance between the conductive tissue contacting surfaces (electrodes).As can be appreciated, both of these parameters are affected by thethickness of the vessel or tissue being sealed. Accurate application ofpressure is important for several reasons: to oppose the walls of thevessel; to reduce the tissue impedance to a low enough value that allowsenough electrosurgical energy through the tissue; to overcome the forcesof expansion during tissue heating; and to contribute to the end tissuethickness which is an indication of a good seal. It has been determinedthat a typical fused vessel wall is optimum between about 0.001 andabout 0.006 inches. Below this range, the seal may shred or tear andabove this range the tissue may not be properly or effectively sealed.

With respect to smaller vessels, the pressure applied becomes lessrelevant and the gap distance between the electrically conductivesurfaces becomes more significant for effective sealing. In other words,the chances of the two electrically conductive surfaces touching duringactivation increases as the tissue thickness and the vessels becomesmaller.

Typically and particularly with respect to endoscopic electrosurgicalprocedures, once a vessel is sealed, the surgeon has to remove thesealing instrument from the operative site, substitute a new instrumentthrough the cannula and accurately sever the vessel along the newlyformed tissue seal. As can be appreciated, this additional step may beboth time consuming (particularly when sealing a significant number ofvessels) and may contribute to imprecise separation of the tissue alongthe sealing line due to the misalignment or misplacement of the severinginstrument along the center of the tissue seal.

Several attempts have been made to design an instrument whichincorporates a knife or blade member which effectively severs the tissueafter forming a tissue seal. For example, U.S. Pat. No. 5,674,220 to Foxet al. discloses a transparent instrument which includes alongitudinally reciprocating knife which severs the tissue once sealed.The instrument includes a plurality of openings which enable directvisualization of the tissue during the treatment and severing processes.This direct visualization allows a user to visually and manuallyregulate the closure force and gap distance between jaw members toreduce and/or limit certain undesirable visual effects known to occurwhen treating vessels, thermal spread, charring, etc. As can beappreciated, the overall success of creating an effective tissue sealwith this instrument is greatly reliant upon the user's expertise,vision, dexterity, and experience in judging the appropriate closureforce, gap distance and length of reciprocation of the knife touniformly, consistently and effectively seal the vessel and separate thetissue at the seal along an ideal cutting plane.

U.S. Pat. No. 5,702,390 to Austin. et al. discloses an instrument whichincludes a triangularly-shaped electrode which is rotatable from a firstposition to treat tissue to a second position to cut tissue. Again, theuser must rely on direct visualization and expertise to control thevarious effects of treating and cutting tissue.

Thus, a need exists to develop an electrosurgical instrument whichincludes an electrode assembly which enables the surgeon to both sealthe tissue in an effective and consistent manner and subsequentlyseparate the tissue along the tissue seal without re-grasping the tissueor removing the instrument from the operating cavity.

SUMMARY

The present disclosure relates to an end effector assembly for use withan instrument for sealing vessel and cutting vessels and/or tissue andincludes a pair of opposing first and second jaw members which aremovable relative to one another from a first position wherein the jawmembers are disposed in spaced relation relative to one another to asecond position wherein the jaw members cooperate to graspvessels/tissue therebetween. Preferably, each jaw member includes a pairof spaced apart, electrically conductive vessel/tissue sealing surfacesextending along a length thereof. Each pair of vessel/tissue sealingsurfaces is connected to a source of electrosurgical energy such thatthe vessel/tissue sealing surfaces are capable of conductingelectrosurgical energy through vessels/tissue held therebetween toeffect a vessel/tissue seal.

The end effector assembly also includes an insulator disposed betweeneach pair of electrically conductive sealing surfaces. In one embodimentaccording to the present disclosure, at least one of the insulators isconfigured to at least partially extend to a position which is at leastsubstantially flush with the cutting element. In yet another embodiment,a second electrically conductive cutting element is disposed within theinsulator of the second jaw member which opposes the first electricallyconductive cutting element. In this instance, the first and secondelectrically conductive cutting elements when disposed on opposite sidesof tissue form the gap distance between electrically conductive sealingsurfaces when the jaw members are disposed in the second position

The first jaw member includes an electrically conductive cutting elementdisposed within the insulator of the first jaw member which is disposedin general vertical registration with the insulator on the second jawmember. The cutting element extends from the first electricallyconductive sealing surface towards the second electrically conductivesealing surface and is configured to create a gap between theelectrically conductive sealing surfaces when the jaw members aredisposed in the second position for sealing vessel/tissue. The cuttingelement is inactive during the sealing process while the pair of spacedapart electrically conductive sealing surfaces on the first jaw memberare energized to a different potential from the corresponding pair ofspaced apart electrically conductive sealing surfaces on the second jawmember such that electrosurgical energy can be transferred through thetissue to effect a vessel/tissue seal.

The end effector assembly is designed such that the cutting element isenergized to a first potential during the cutting process and at leastone electrically conductive sealing surface on the first jaw member andat least one electrically conductive sealing surface on the second jawmember are energized to a different potential such that electrosurgicalenergy can be transferred through the vessels/tissue to effect avessel/tissue cut.

Preferably, the cutting element and sealing processes are automaticallycontrolled by an electrosurgical energy source. In one embodimentaccording to the present disclosure, it is envisioned that the potentialof the electrically conductive sealing surface of the first jaw memberand the potential of the cutting element are independently activatableby the surgeon. In another embodiment, the electrical potential of thecutting element and the electrical potential of at least oneelectrically conductive sealing surface are automatically configured forcutting when the surgeon selectively activates a trigger. Preferably,the cutting element is substantially dull and only capable of cuttingvessels/tissue through electrosurgical activation.

In yet another embodiment according to the present disclosure a smartsensor is included for determining seal quality prior to cutting. Thesmart sensor may include either an audible or visual indicator forindicating seal quality. Preferably, the smart sensor automaticallyswitches electrosurgical energy to the cutting element once thevessel/tissue is sealed.

In still yet another embodiment of the end effector assembly accordingto the present disclosure a first switch is included for energizing theelectrically conductive sealing surfaces to effect vessel/tissue sealingand a trigger is included for energizing the cutting element and atleast one of the electrically conductive sealing surfaces to effectvessel/tissue cutting.

Another embodiment according to the present disclosure includes an endeffector assembly for use with an instrument for sealing and/or cuttingvessels or tissue which includes a pair of opposing first and second jawmembers which movable relative to one another from a first positionwherein the jaw members are disposed in spaced relation relative to oneanother to a second position wherein the jaw members cooperate to graspvessel/tissue therebetween. Each jaw member of the end effector assemblyincludes a pair of spaced apart, electrically conductive sealingsurfaces which extend along a length thereof. Each sealing surface isconnected to a source of electrosurgical energy such that the sealingsurfaces are capable of conducting electrosurgical energy throughvessel/tissue held therebetween to effect a vessel/tissue seal. The endeffector assembly further includes an insulator disposed between eachpair of electrically conductive sealing surfaces.

Preferably, the first jaw member includes an electrically conductivecutting element disposed within or disposed on the insulator of thefirst jaw member, the electrically conductive cutting element isdisposed in general vertical registration to the insulator on the secondjaw member. At least one stop member is included which is operativelyassociated with one of the first and second jaw members and isdimensioned to create a gap between the electrically conductive sealingsurfaces when the jaw members close for sealing vessel/tissue.

Preferably, the cutting element is inactive during the sealing processand the pair of spaced apart electrically conductive sealing surfaces onthe first jaw member are energized to a different potential from thecorresponding pair of spaced apart electrically conductive sealingsurfaces on the second jaw member such that electrosurgical energy canbe transferred through the vessel/tissue to effect a vessel/tissue seal.During the cutting process, the cutting element is energized to a firstpotential and at least one electrically conductive sealing surface onthe first jaw member and at least one electrically conductive sealingsurface on the second jaw member are energized to a different potentialsuch that electrosurgical energy can be transferred through thevessel/tissue to effect a vessel/tissue cut.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the subject instrument are described herein withreference to the drawings wherein:

FIG. 1A is a right, perspective view of an endoscopic bipolar forcepshaving a housing, a shaft and a pair of jaw members affixed to a distalend thereof, the jaw members including an electrode assembly disposedtherebetween;

FIG. 1B is a left, perspective view of an open bipolar forceps showing apair of first and second shafts each having a jaw member affixed to adistal end thereof with an electrode assembly disposed therebetween;

FIG. 2 is an enlarged view of the area of detail of FIG. 1B

FIGS. 3A-3F are enlarged, schematic end views showing a variety ofdifferent electrode assemblies according to the present disclosure withelectrical potentials identified for electrical cutting;

FIG. 4A is an enlarged, schematic end view showing one electrodeassembly configuration with tissue disposed between the jaw members;

FIG. 4B is a schematic end view showing the area of detail of FIG. 4A;

FIGS. 4C-4J are enlarged, schematic end views showing variousconfigurations for an upper jaw member to promote electrical cutting;

FIG. 5 is a schematic end view showing an alternate configuration of anelectrode assembly according to the present invention with theelectrical potentials for both the sealing phase and the cutting phaseidentified;

FIGS. 6A-6D are enlarged, schematic end views showing alternateconfigurations of the electrode assembly according to the presentinvention with the electrical potentials for both the sealing mode andthe cutting mode identified; and

FIGS. 7A-7E are enlarged, schematic end views showing variousconfigurations for the lower jaw member to promote electrical cutting.

DETAILED DESCRIPTION

For the purposes herein, vessel/tissue cutting or vessel/tissue divisionis believed to occur when heating of the vessel/tissue leads toexpansion of intracellular and/or extra-cellular fluid, which may beaccompanied by cellular vaporization, desiccation, fragmentation,collapse and/or shrinkage along a so-called “cut zone” in thevessel/tissue. By focusing the electrosurgical energy and heating in thecut zone, the cellular reactions are localized creating a fissure.Localization is achieved by regulating the vessel/tissue condition andenergy delivery which may be controlled by utilizing one or more of thevarious geometrical electrode and insulator configurations describedherein. The cut process may also be controlled by utilizing a generatorand feedback algorithm (and one or more of the hereindescribedgeometrical configurations of the electrode and insulator assemblies)which increases the localization and maximizes the so-called “cuttingeffect”.

For example, it is envisioned that the below described factorscontribute and/or enhance vessel/tissue division using electrosurgicalenergy. Each of the factors described below may be employed individuallyor in any combination to achieve a desired cutting effect. For thepurposes herein the term “cut effect” or “cutting effect” refers to theactual division of tissue by one or more of the electrical orelectromechanical methods or mechanisms described below. The term“cutting zone” or “cut zone” refers to the region of vessel/tissue wherecutting will take place. The term “cutting process” refers to steps thatare implemented before, during and/or after vessel/tissue division thattend to influence the vessel/tissue as part of achieving the cut effect.

For the purposes herein the terms “tissue” and “vessel” may be usedinterchangeably since it is believed that the present disclosure may beemployed to seal and cut tissue or seal and cut vessels utilizing thesame inventive principles described herein.

It is believed that the following factors either alone or incombination, play an important role in dividing tissue:

-   -   Localizing or focusing electrosurgical energy in the cut zone        during the cutting process while minimizing energy effects to        surrounding tissues;    -   Focusing the power density in the cut zone during the cutting        process;    -   Creating an area of increased temperature in the cut zone during        the cutting process (e.g., heating that occurs within the tissue        or heating the tissue directly with a heat source);    -   Pulsing the energy delivery to influence the tissue in or around        the cut zone. “Pulsing” involves as a combination of an “on”        time and “off” time during which the energy is applied and then        removed repeatedly at any number of intervals for any amount of        time. The pulse “on” and “off” time may vary between pulses. The        pulse “on” typically refers to a state of higher power delivery        and pulse “off” typically refers to a state of lower power        delivery;    -   Spiking the energy delivery creates a momentary condition of        high energy application with an intent to influence the tissue        in or around the cut zone during the cut process. The momentary        condition may be varied to create periods of high energy        application;    -   Conditioning the tissue before or during the cutting process to        create more favorable tissue conditions for cutting. This        includes tissue pre-heating before the cutting processes and        tissue rehydration during the cutting process;    -   Controlling the tissue volume in or around the cut zone to        create more favorable conditions for tissue cutting;    -   Controlling energy and power delivery to allow vaporization to        enhance and or contribute to the cutting process. For example,        controlling the energy delivery to vaporize both intracellular        and/or extracellular fluids and/or other cellular materials and        foreign fluids within the cut zone;    -   Fragmenting the tissue or cellular material during the cutting        process to enhance tissue division in the cut zone;    -   Melting or collapsing the tissue or cellular material during the        cutting process to enhance tissue division in the cut zone. For        example, melting the tissue to create internal stress within the        tissue to induce tissue tearing;    -   Controlling tissue temperature, arcing, power density and/or        current density during the cutting process to enhance tissue        division in the cut zone;    -   Applying various mechanical elements to the tissue such as        pressure, tension and/or stress (either internally or        externally) to enhance the cutting process; and    -   Utilizing various other tissue treatments before or during the        cutting process to enhance tissue cutting, e.g., tissue sealing,        cauterization and/or coagulation.

Many of the electrode assemblies described herein employ one or more ofthe above-identified factors for enhancing tissue division. For example,many of the electrode assemblies described herein utilize variousgeometrical configurations of electrodes, cutting elements, insulators,partially conductive materials and semiconductors to produce or enhancethe cutting effect. In addition, by controlling or regulating theelectrosurgical energy from the generator in any of the ways describedabove, tissue cutting may be initiated, enhanced or facilitated withinthe tissue cutting zone. For example, it is believed that thegeometrical configuration of the electrodes and insulators may beconfigured to produce a so-called “cut effect” which may be directlyrelated to the amount of vaporization or fragmentation at a point in thetissue or the power density, temperature density and/or mechanicalstress applied to a point in the tissue. The geometry of the electrodesmay be configured such that the surface area ratios between theelectrical poles focus electrical energy at the tissue. Moreover, it isenvisioned that the geometrical configurations of the electrodes andinsulators may be designed such that they act like electrical sinks orinsulators to influence the heat effect within and around the tissueduring the sealing or cutting processes.

Referring now to FIGS. 1A and 1B, FIG. 1A depicts a bipolar forceps 10for use in connection with endoscopic surgical procedures and FIG. 1Bdepicts an open forceps 100 contemplated for use in connection withtraditional open surgical procedures. For the purposes herein, either anendoscopic instrument or an open instrument may be utilized with theelectrode assembly described herein. Obviously, different electrical andmechanical connections and considerations apply to each particular typeof instrument, however, the novel aspects with respect to the electrodeassembly and its operating characteristics remain generally consistentwith respect to both the open or endoscopic designs.

FIG. 1A shows a bipolar forceps 10 for use with various endoscopicsurgical procedures and generally includes a housing 20, a handleassembly 30, a rotating assembly 80, a switch assembly 70 and anelectrode assembly 105 having opposing jaw members 110 and 120 whichmutually cooperate to grasp, seal and divide tubular vessels andvascular tissue. More particularly, forceps 10 includes a shaft 12 whichhas a distal end 16 dimensioned to mechanically engage the electrodeassembly 105 and a proximal end 14 which mechanically engages thehousing 20. The shaft 12 may include one or more known mechanicallyengaging components which are designed to securely receive and engagethe electrode assembly 105 such that the jaw members 110 and 120 arepivotable relative to one another to engage and grasp tissuetherebetween.

The proximal end 14 of shaft 12 mechanically engages the rotatingassembly 80 (not shown) to facilitate rotation of the electrode assembly105. In the drawings and in the descriptions which follow, the term“proximal”, as is traditional, will refer to the end of the forceps 10which is closer to the user, while the term “distal” will refer to theend which is further from the user. Details relating to the mechanicallycooperating components of the shaft 12 and the rotating assembly 80 aredescribed in commonly-owned U.S. patent application Ser. No. 10/460,926entitled “VESSEL SEALER AND DIVIDER FOR USE WITH SMALL TROCARS ANDCANNULAS” filed on Jun. 13, 2003 the entire contents of which areincorporated by reference herein.

Handle assembly 30 includes a fixed handle 50 and a movable handle 40.Fixed handle 50 is integrally associated with housing 20 and handle 40is movable relative to fixed handle 50 to actuate the opposing jawmembers 110 and 120 of the electrode assembly 105 as explained in moredetail below. Movable handle 40 and switch assembly 70 are preferably ofunitary construction and are operatively connected to the housing 20 andthe fixed handle 50 during the assembly process. Housing 20 ispreferably constructed from two components halves 20 a and 20 b whichare assembled about the proximal end of shaft 12 during assembly. Switchassembly is configured to selectively provide electrical energy to theelectrode assembly 105.

As mentioned above, electrode assembly 105 is attached to the distal end16 of shaft 12 and includes the opposing jaw members 110 and 120.Movable handle 40 of handle assembly 30 imparts movement of the jawmembers 110 and 120 from an open position wherein the jaw members 110and 120 are disposed in spaced relation relative to one another, to aclamping or closed position wherein the jaw members 110 and 120cooperate to grasp tissue therebetween.

Referring now to FIG. 1B, an open forceps 100 includes a pair ofelongated shaft portions 112 a and 112 b each having a proximal end 114a and 114 b, respectively, and a distal end 116 a and 116 b,respectively. The forceps 100 includes jaw members 120 and 110 whichattach to distal ends 116 a and 116 b of shafts 112 a and 112 b,respectively. The jaw members 110 and 120 are connected about pivot pin119 which allows the jaw members 110 and 120 to pivot relative to oneanother from the first to second positions for treating tissue. Theelectrode assembly 105 is connected to opposing jaw members 110 and 120and may include electrical connections through or around the pivot pin119. Examples of various electrical connections to the jaw members areshown in commonly-owned U.S. patent application Ser. Nos. 10/474,170,10/116,824, 10/284,562 10/472,295, 10/116,944, 10/179,863 and10/369,894, the contents of all of which are hereby incorporated byreference herein.

Preferably, each shaft 112 a and 112 b includes a handle 117 a and 117 bdisposed at the proximal end 114 a and 114 b thereof which each define afinger hole 118 a and 118 b, respectively, therethrough for receiving afinger of the user. As can be appreciated, finger holes 118 a and 118 bfacilitate movement of the shafts 112 a and 112 b relative to oneanother which, in turn, pivot the jaw members 110 and 120 from the openposition wherein the jaw members 110 and 120 are disposed in spacedrelation relative to one another to the clamping or closed positionwherein the jaw members 110 and 120 cooperate to grasp tissuetherebetween. A ratchet 130 is preferably included for selectivelylocking the jaw members 110 and 120 relative to one another at variouspositions during pivoting.

More particularly, the ratchet 130 includes a first mechanical interface130 a associated with shaft 112 a and a second mating mechanicalinterface associated with shaft 112 b. Preferably, each positionassociated with the cooperating ratchet interfaces 130 a and 130 b holdsa specific, i.e., constant, strain energy in the shaft members 112 a and112 b which, in turn, transmits a specific closing force to the jawmembers 110 and 120. It is envisioned that the ratchet 130 may includegraduations or other visual markings which enable the user to easily andquickly ascertain and control the amount of closure force desiredbetween the jaw members 110 and 120.

As best seen in FIG. 1B, forceps 100 also includes an electricalinterface or plug 200 which connects the forceps 100 to a source ofelectrosurgical energy, e.g., an electrosurgical generator (not shown).Plug 200 includes at least two prong members 202 a and 202 b which aredimensioned to mechanically and electrically connect the forceps 100 tothe electrosurgical generator 500 (See FIG. 1A). An electrical cable 210extends from the plug 200 and securely connects the cable 210 to theforceps 100. Cable 210 is internally divided within the shaft 112 b totransmit electrosurgical energy through various electrical feed paths tothe electrode assembly 105.

One of the shafts, e.g., 112 b, includes a proximal shaftconnector/flange 119 which is designed to connect the forceps 100 to asource of electrosurgical energy such as an electrosurgical generator500. More particularly, flange 119 mechanically secures electrosurgicalcable 210 to the forceps 100 such that the user may selectively applyelectrosurgical energy as needed.

As best shown in the schematic illustration of FIG. 2, the jaw members110 and 120 of both the endoscopic version of FIG. 1A and the openversion of FIG. 1B are generally symmetrical and include similarcomponent features which cooperate to permit facile rotation about pivot19, 119 to effect the grasping and sealing of tissue. Each jaw member110 and 120 includes an electrically conductive tissue contactingsurface 112 and 122, respectively, which cooperate to engage the tissueduring sealing and cutting. At least one of the jaw members, e.g., jawmember 120, includes a electrically energizable cutting element 127disposed therein which is explained in detail below. Together and asshown in the various figure drawings described hereafter, the electrodeassembly 105 includes the combination of the sealing electrodes 112 and122 and the cutting element(s) 127.

The various electrical connections of the electrode assembly 105 arepreferably configured to provide electrical continuity to the tissuecontacting surfaces 110 and 120 and the cutting element(s) 127 throughthe electrode assembly 105. For example, cable lead 210 may beconfigured to include three different leads, namely, leads 207, 208 and209 which carry different electrical potentials. The cable leads 207,208 and 209 are fed through shaft 112 b and connect to variouselectrical connectors (not shown) disposed within the proximal end ofthe jaw member 110 which ultimately connect to the electricallyconductive sealing surfaces 112 and 122 and cutting element(s) 127. Ascan be appreciated, the electrical connections may be permanentlysoldered to the shaft 112 b during the assembly process of a disposableinstrument or, alternatively, selectively removable for use with areposable instrument. Commonly owned U.S. patent application Ser. Nos.10/474,170, 10/116,824 and 10/284,562 all disclose various types ofelectrical connections which may be made to the jaw members 110 and 120through the shaft 112 b the contents of all of which being herebyincorporated by reference wherein. In addition and with respect to thetypes of electrical connections which may be made to the jaw members 110and 120 for endoscopic purposes, commonly-owned U.S. patent applicationSer. Nos. 10/472,295, 10/116,944, 10/179,863 and 10/369,894 all discloseother types of electrical connections which are hereby incorporated byreference herein in their entirety.

The various electrical connections from lead 210 are preferablydielectrically insulated from one another to allow selective andindependent activation of either the tissue contacting surfaces 112 and122 or the cutting element 127 as explained in more detail below.Alternatively, the electrode assembly 105 may include a single connectorwhich includes an internal switch (not shown) to allow selective andindependent activation of the tissue contacting surfaces 112, 122 andthe cutting element 127. Preferably, the leads 207, 208 and 209 (and/orconductive pathways) do not encumber the movement of the jaw members 110and 120 relative to one another during the manipulation and grasping oftissue. Likewise, the movement of the jaw members 110 and 120 do notunnecessarily strain the lead connections.

As best seen in FIGS. 2-3F, various electrical configurations of theelectrode assembly 105 are shown which are designed to effectively sealand cut tissue disposed between the sealing surfaces 112 and 122 and thecutting elements 127 of the opposing jaw members 110 and 120,respectively. More particularly and with respect to FIGS. 2 and 3A, jawmembers 110 and 120 include conductive tissue contacting surfaces 112and 122, respectively, disposed along substantially the entirelongitudinal length thereof (i.e., extending substantially from theproximal to distal end of the respective jaw member 110 and 120). It isenvisioned that tissue contacting surfaces 112 and 122 may be attachedto the jaw member 110, 120 by stamping, by overmolding, by casting, byovermolding a casting, by coating a casting, by overmolding a stampedelectrically conductive sealing plate and/or by overmolding a metalinjection molded seal plate or in other ways customary in the art. Allof these manufacturing techniques may be employed to produce jaw member110 and 120 having an electrically conductive tissue contacting surface112 and 122 disposed thereon for contacting and treating tissue.

With respect to FIG. 3A, the jaw members 110 and 120 both include aninsulator or insulative material 113 and 123, respectively, disposedbetween each pair of electrically conductive sealing surfaces on eachjaw member 110 and 120, i.e., between pairs 112 a and 112 b and betweenpairs 122 a and 122 b. Each insulator 113 and 123 is generally centeredbetween its respective tissue contacting surface 112 a, 112 b and 122 a,122 b along substantially the entire length of the respective jaw member110 and 120 such that the two insulators 113 and 123 generally opposeone another.

One or both of the insulators 113, 123 may be made from a ceramicmaterial due to its hardness and inherent ability to withstand hightemperature fluctuations. Alternatively, one or both of the insulators113, 123 may be made from a material having a high Comparative TrackingIndex (CTI) having a value in the range of about 300 to about 600 volts.Examples of high CTI materials include nylons and syndiotacticpolystryrenes such as QUESTRA® manufactured by DOW Chemical. Othermaterials may also be utilized either alone or in combination, e.g.,Nylons, Syndiotactic-polystryrene (SPS), Polybutylene Terephthalate(PBT), Polycarbonate (PC), Acrylonitrile Butadiene Styrene (ABS),Polyphthalamide (PPA), Polymide, Polyethylene Terephthalate (PET),Polyamide-imide (PAI), Acrylic (PMMA), Polystyrene (PS and HIPS),Polyether Sulfone (PES), Aliphatic Polyketone, Acetal (POM) Copolymer,Polyurethane (PU and TPU), Nylon with Polyphenylene-oxide dispersion andAcrylonitrile Styrene Acrylate.

At least one jaw member 110 and/or 120 includes an electricallyconductive cutting element 127 disposed substantially within or disposedon the insulator 113, 123. As described in detail below, the cuttingelement 127 (in many of the embodiments described hereinafter) plays adual role during the sealing and cutting processes, namely: 1) toprovide the necessary gap distance between conductive surfaces 112 a,112 b and 122 a, 122 b during the sealing process; and 2) toelectrically energize the tissue along the previously formed tissue sealto cut the tissue along the seal. With respect to FIG. 3A, the cuttingelements 127 a, 127 b are electrically conductive, however, it isenvisioned that one or both of the cutting elements 127 a, 127 b may bemade from an insulative material with a conductive coating disposedthereon or one (or both) of the cutting elements may be non-conductive(See, e.g., FIG. 4A). Preferably, the distance between the cuttingelement(s) 127 a and the opposing cutting element 127 b (or the opposingreturn electrode in some cases) is within the range of about 0.008inches to about 0.015 inches to optimize the cutting effect.

The general characteristics of the jaw members 110 and 120 and theelectrode assembly 105 will initially be described with respect to FIG.3A while the changes to the other envisioned embodiments disclosedherein will become apparent during the description of each individualembodiment. Moreover, all of the following figures show the variouselectrical configurations and polarities during the cutting phase only.During the so called “sealing phase”, the jaw members 110 and 120 areclosed about tissue and the cuffing elements 127 and 127 b forms therequisite gap between the opposing sealing surfaces 112 a, 122 a and 112b, 122 b. During activation of the sealing phase, the cutting elements127 a and 127 b are not necessarily energized such that the majority ofthe current is concentrated between opposing sealing surfaces, 112 a and122 a and 112 b and 122 b to effectively seal the tissue. It is alsoenvisioned that stop members 1160 a and 1160 b may be employed toregulate the gap distance between the sealing surfaces in lieu of thecutting elements 127 a and 127 b. The stop members 1160 a and 1160 b maybe disposed on the sealing surfaces 1112 a, 1122 a and 1112 b, 1122 b(See FIG. 4E), adjacent the sealing surfaces 1112 a, 1122 a and 1112 b,1122 b or on the insulator(s) 1113, 1123.

The cuffing elements 127 a and 127 b are preferably configured to extendfrom their respective insulators 113 and 123, respectively and extendbeyond the tissue contacting surfaces 112 a, 112 b and 122 a and 122 bsuch that the cutting elements 127 a and 127 b act as stop members(i.e., creates a gap distance “G” (See FIG. 3A) between opposingconductive sealing surfaces 112 a, 122 a and 112 b, 122 b) which asmentioned above promotes accurate, consistent and effective tissuesealing. As can be appreciated, the cutting elements 127 a and 127 balso prevent the opposing tissue contacting surfaces 112 a, 122 a and112 b, 122 b from touching which eliminates the chances of the forceps10, 100 shorting during the sealing process.

As mentioned above, two mechanical factors play an important role indetermining the resulting thickness of the sealed tissue andeffectiveness of a tissue seal, i.e., the pressure applied betweenopposing jaw members 110 and 120 and the gap distance “G” between, theopposing tissue contacting surfaces 112 a, 122 a and 112 b, 122 b duringthe sealing process. Preferably and with particular respect to vessels,the cutting element 127 (or cutting elements 127 a and 127 b) extendsbeyond the tissue contacting surfaces 112 a, 112 b and/or 122 a, 122 bto yield a consistent and accurate gap distance “G” during sealingwithin the range of about 0.001 inches to about 0.006 inches and, morepreferably, within the range of about 0.002 inches and about 0.003inches. Other gap ranges may be preferable with other tissue types suchas bowel or large vascular structures. As can be appreciated, whenutilizing one cutting element (as with some of the disclosed embodimentsherein), e.g., 127, the cutting element 127 would be configured toextend beyond the sealing surfaces 112 a, 112 b and 122 a, 122 b toyield a gap distance within the above working range. When two opposingcutting elements are utilized, e.g., 127 a and 127 b, the combination ofthese cutting elements 127 a and 127 b yield a gap distance within theabove working range during the sealing process.

With respect to FIG. 3A, the conductive cutting elements 127 a and 127 bare oriented in opposing, vertical registration within respectiveinsulators 113 and 123 of jaw members 110 and 120. It is envisioned thatthe cutting elements 127 a and 127 b are substantially dull which, ascan be appreciated, does not inhibit the sealing process (i.e.,premature cutting) during the sealing phase of the electrosurgicalactivation. In other words, the surgeon is free to manipulate, grasp andclamp the tissue for sealing purposes without the cuffing elements 127 aand 127 b mechanically cutting into the tissue. Moreover in thisinstance, tissue cutting can only be achieved through either: 1) acombination of mechanically clamping the tissue between the cuttingelements 127 a and 127 b and applying electrosurgical energy from thecutting elements 127 a and 127 b, through the tissue and to the returnelectrodes, i.e., the electrically conductive tissue contacting surfaces112 b and 122 b as shown in FIG. 3A; or 2) applying electrosurgicalenergy from the cutting elements 127 a and 127 b through the tissue andto the return tissue contacting surfaces 112 b and 122 b.

It is envisioned that the geometrical configuration of the cuttingelements 127 a and 127 b play an important role in determining theoverall effectiveness of the tissue cut. For example, the power densityand/or current concentration around the cutting elements 127 a and 127 bis based upon the particular geometrical configuration of the cuttingelements 127 a and 127 b and the cutting elements' 127 a and 127 bproximity to the return electrodes, i.e., tissue contacting surfaces 112b and 122 b. Certain geometries of the cutting elements 127 a and 127 bmay create higher areas of power density than other geometries.Moreover, the spacing of the return electrodes 112 b and 122 b to thesecurrent concentrations effects the electrical fields through the tissue.Therefore, by configuring the cutting elements 127 a and 127 b and therespective insulators 113 and 123 within close proximity to one another,the electrical power density remains high which is ideal for cutting andthe instrument will not short due to accidental contact betweenconductive surfaces. As can be appreciated, the relative size of thecutting elements 127 a and 127 b and/or the size of the insulator 113and 123 may be selectively altered depending upon a particular ordesired purpose to produce a particular surgical effect.

In addition, the cutting element 127 a (and/or 127 b) may beindependently activated by the surgeon or automatically activated by theGenerator once sealing is complete. A safety algorithm may be employedto assure that an accurate and complete tissue seal is formed beforecutting. An audible or visual indicator (not shown) may be employed toassure the surgeon that an accurate seal has been formed and the surgeonmay be required to activate a trigger (or deactivate a safety) beforecutting. For example, a smart sensor or feedback algorithm 1999 (SeeFIG. 5) may be employed to determine seal quality prior to cutting. Thesmart sensor or feedback loop 1999 may also be configured toautomatically switch electrosurgical energy to the cutting element 127 a(and/or 127 b) once the smart sensor 1999 determines that the tissue isproperly sealed. It is also envisioned that the electrical configurationof the electrically conductive sealing surfaces 112 a, 112 b and 122 a,122 b may be automatically or manually altered during the sealing andcutting processes to effect accurate and consistent tissue sealing andcutting.

Turning now to the embodiments of the electrode assembly 105 asdisclosed herein which show the various polarities during the tissuecutting phase, FIG. 3A as mentioned above includes first and second jawmembers 110 and 120 having an electrode assembly 105 disposed thereon.More particularly, the electrode assembly 105 includes firstelectrically conductive sealing surfaces 112 a and 112 b each disposedin opposing registration with second electrically conductive sealingsurfaces 122 a and 122 b on jaw members 110 and 120, respectively.Insulator 113 electrically isolates sealing surfaces 112 a and 112 bfrom one another allowing selective independent activation of thesealing surfaces 112 a and 112 b. Insulator 123 separates sealingsurfaces 122 a and 122 b from one another in a similar manner therebyallowing selective activation of sealing surfaces 122 a and 122 b.

Preferably each insulator 113 and 123 is set back a predetermineddistance between the sealing surfaces 112 a, 112 b and 122 a, 122 b todefine a recess 149 a, 149 b and 159 a, 159 b, respectively, which, asmentioned above, effects the overall power densities between theelectrically activated surfaces during both the sealing and cuttingphases. Cutting element 127 a is disposed within and/or deposited oninsulator 113 and extends inwardly therefrom to extend beyond thesealing surfaces 112 a, 112 b by a predetermined distance. In theembodiments wherein only one cutting element, e.g., 127 a is shown, thecutting element 127 a extends beyond the sealing surfaces 112 a, 112 band 122 a and 122 b to define the aforementioned gap range between theopposing sealing surfaces 112 a, 122 a and 112 b and 122 b. When two (ormore) cutting elements 127 a and 127 b are employed (i.e., at least onedisposed within each insulator 113 and 123) the combination of thecutting elements 127 a and 127 b yield the desired gap distance withinthe working gap range.

During sealing, the opposing sealing surfaces 112 a, 122 a and 112 b,122 b are activated to seal the tissue disposed therebetween to createtwo tissue seals on either side of the insulators 113 and 123. Duringthe cutting phase, the cutting elements 127 a and 127 b are energizedwith a first electrical potential “+” and the right opposing sealingsurfaces 112 b and 122 b are energized with a second electricalpotential “−”. This creates a concentrated electrical path between thepotentials “+” and “−” through the tissue to cut the tissue between thepreviously formed tissue seals. Once the tissue is cut, the jaw members110 and 120 are opened to release the two tissue halves.

FIG. 3B discloses another embodiment according to the present disclosurewhich includes similar elements as described above with respect to FIG.3A, namely, sealing surfaces 312 a, 312 b and 322 a, 322 b, insulators313 and 323 and cutting elements 327 a and 327 b with the exception thatthe left side of each insulator 313 and 323 is extended beyond sealingsurfaces 312 a and 322 a to a position which is flush with the cuttingelements 327 a and 327 b. The right side of each insulator 313 and 323is set back from sealing surfaces 312 a and 312 b, respectively. It isenvisioned that configuring the electrode assembly 305 in this fashionwill reduce stray current concentrations between electrically conductivesurfaces 312 a, 312 b and 322 a, 322 b and cutting elements 327 a and327 b especially during the cutting phase.

FIG. 3C discloses yet another embodiment according to the presentdisclosure and includes similar elements as above, namely, sealingsurfaces 412 a, 412 b and 422 a, 422 b, insulators 413 and 423 andcutting elements 327 a and 327 b. With this particular embodiment,during the cutting phase, both sets of opposing sealing surfaces 412 a,422 a and 412 b, 422 b are energized with the second electricalpotential “−” and the cutting elements 427 a and 427 b are energized tothe first electrical potential “+”. It is believed that this electrodeassembly 405 will create concentrated electrical paths between thepotentials “+” and “−” through the tissue to cut the tissue between thepreviously formed tissue seals.

FIG. 3D shows an electrode assembly 505 configuration similar to FIG. 3Bwith a similar electrical configuration to the embodiment of FIG. 3C.The electrode assembly 505 includes and includes similar components asdescribed above, namely, sealing surfaces 512 a, 512 b and 522 a, 522 b,insulators 513 and 523 and cutting elements 527 a and 527 b. Theopposing sealing electrodes 512 a, 522 b and 512 a, 522 b are energizedto the second electrical potential “−” during the cutting phase, whichas described above is believed to enhance tissue cutting. It isenvisioned that with particular embodiments like FIGS. 3C and 3D, it maybe easier to manufacture the electrode assembly 505 such that all of thesealing surfaces 512 a, 512 b and 522 a, 522 b are energized to the sameelectrical potential rather than employ complicated switching algorithmsand/or circuitry to energize only select sealing surfaces like FIGS. 3Aand 3B.

FIG. 3E shows yet another embodiment of the electrode assembly 605 whichincludes opposing sealing surfaces 612 a, 622 a and 612 b, 622 b,cutting element 627 and insulators 613 and 623. As can be appreciated bythis particular embodiment, the electrode assembly 605 only includes onecutting element 627 disposed within insulator 613 for cutting tissue.The cutting element 627 is disposed opposite insulator 623 whichprovides a dual function during activation of the electrode assembly605: 1) provides a uniform gap between sealing surfaces 612 a, 622 a and612 b, 622 b during the sealing phase; and 2) prevents the electrodeassembly 605 from shorting during the sealing and cutting phases. Duringactivation, the cutting element 627 is energized to a first potential“+” and the opposing sealing surfaces 612 a, 622 a and 612 b, 622 b areenergized to a second electrical potential “−” which creates an area ofhigh power density between the two previously formed tissue seals andcuts the tissue.

FIG. 3F shows yet another alternate embodiment of the electrode assembly705 which includes similar elements as described above, namely, sealingsurfaces 712 a, 712 b and 722 a, 722 b, cutting elements 727 a and 727 band insulators 713 and 723. During activation, only three of the foursealing surfaces are energized to the second potential “−”, e.g.,sealing surfaces 712 a, 712 b and 722 b while the cutting elements 727 aand 727 b are energized to the first potential “+”. It is envisionedthat during the cutting phase, this particular electrode assembly 705arrangement will produce a diagonally-oriented, left-to-right cut linebetween the previously formed tissue seals which may be suited for aparticular surgical purpose.

FIGS. 4A and 4B shows yet another embodiment of the electrode assembly805 according to the present disclosure showing tissue disposed betweenthe two jaw members 810 and 820 prior to activation of the sealingsurfaces 812 a, 812 b and 822 a, 822 b. With this particular embodiment,the insulators 813 and 823 are configured to have opposing triangularlike cross sections which essentially “pinch” the tissue between theinsulators 813 and 823 when tissue is grasped between jaw members 810and 820. During sealing, energy is applied to the tissue through theopposing sealing plates 812 a, 822 a and 812 b, 822 b to effect twotissue seals on either side of the insulators 813 and 823. During thecutting phase, sealing electrodes 812 a and 822 a are energized to afirst potential “+” and sealing plates 812 b and 822 b are energized tothe second electrical potential “−” such that energy flows in thedirection of the indicated arrow “A”. In other words, it is believedthat the pinching of the tissue tends to control or direct the energyconcentration to specific tissue areas to effect tissue cutting.

Turning now to FIGS. 4C-4J which show various geometrical configurationsfor the upper jaw member 910 for the electrode assembly 905 which may beutilized with a symmetrical or asymmetrical lower jaw member (not shown)to effectively seal and subsequently cut tissue. Using the variousgeometries of the jaw members tends to “pinch” the tissue during sealingprior to separation which is envisioned will enhance the tissue cuttingprocess especially when the pinched tissue areas are subject to highpower densities. For the purposes herein, the pinch may be described asthe area of smallest tissue volume anywhere between the active tissuepoles. Typically, the pinched tissue area is associated with highpressure. Many of the below described jaw configurations illustrate thepinch concept and are envisioned to utilize a variety of polarityconfigurations to enhance or facilitate cutting. For the purposes ofclarification, only the polarity associated with the cutting phase isdepicted on each figure.

Moreover, it is envisioned that any combination of electrical potentialas hereinbefore described may be utilized with the various jaw members(and each jaw members opposing jaw member) to effectively seal tissueduring a first electrical phase and cut tissue during a subsequentelectrical phase. As such, the illustrated jaw members are labeled witha first electrical potential “+”, however, it is envisioned that thelower jaw member inclusive of the sealing surfaces and cutting elements(which may or may not be a mirror image of the upper jaw member) may beenergized with any combination of first and second electricalpotential(s) (or other electrical potentials) to effectively seal andsubsequently cut tissue disposed between the jaw members.

FIG. 4C shows one particular upper jaw member 910 which includes asealing surface 912 having a U-shaped recess 921 defined therein forhousing insulator 913. A cutting element 927 is disposed withininsulator 913 and is dimensioned to extend beyond the sealing surface912. The cutting element 927 may be an electrode or may be made from apartially conductive material. FIG. 4D shows a jaw member 1010 whichforms part of an electrode assembly 1005 which includes two sealingsurfaces 1012 a and 1012 b with an insulator 1013 disposed therebetween.The insulator 1013 includes a cutting element 1027 disposed thereinwhich extends beyond the sealing surfaces 1012 a and 1012 b much likethe embodiments described above with respect to FIGS. 3A-3F. Again thecutting element 1027 may be an electrode or made from a semi-conductormaterial. However and as mentioned above, a differentgeometrically-shaped jaw member may be disposed opposite jaw member 1010with different electrical potentials to produce a particular sealing andcutting effect.

FIGS. 4E-4J show various geometrical configurations of at least one jawmember which is configured to both seal tissue during a first sealingphase and cut tissue during a subsequent cutting phase. In eachinstance, the particular geometrical configuration of the insulator isdesigned to focus current into high areas of power density to produce acutting effect and/or reduce the likelihood of current straying toadjacent tissue which may ultimately damage the adjacent tissuestructures.

For example, FIG. 4E shows a jaw member 1110 which may be utilized withthe electrode assembly 1105 which includes sealing surfaces 1112 a and1112 b which are separated by a partially conductive material 1113. Amirror-like jaw member 1120 is shown in opposition to jaw member 1110and includes similar elements, namely, sealing surfaces 1122 a and 1122b and partially conductive material 1123. In this particular embodiment,the partially conductive materials 1113 and 1123 are generally roundedto include and apexes 1151 a and 1151 b, respectively, which extendbeyond the sealing surfaces 1112 a, 1112 b and 1122 a, 1122 b. Thepartially conductive materials 1113 and 1123 are preferably made from amaterial which have conductive properties which over time generate areasof high power density at the apexes 1151 a and 1151 b to cut tissuedisposed thereunder. A series of stop members 1160 a and 1160 andpreferably disposed on surfaces 1112 a and 1122 b and prevent the apexes1151 a and 1151 b from touching and shorting.

It is envisioned that during the sealing phase (not shown) the partiallyconductive materials 1113 and 1123 are not energized and will generallyact more as insulating materials since by its nature it is onlysemi-conductive and are not as conductive as sealing surfaces 1112 a,1112 b and 1122 a, 1122 b. In other words, the current will be suppliedto the sealing plates 1112 a, 1112 b and 1122 a, 1122 b and not directlyto the partially conductive materials 1113 and 1123 thereby producingthe majority of the electrical effect between the opposing sealingplates 1112 a, 1122 a and 1112 b, 1122 b of the jaw members 1110 and1120. During the cutting phase (as shown), an electrical potential issupplied directly to the partially conductive materials 1113 and 1123which is believed will make them more conductive and which produce areasof high power density in the vicinity of the apexes 1151 a and 1151 b tocut the tissue.

For example, partially conductive material 1113 is supplied with a firstpotential and partially conductive material 1123 is supplied with asecond potential to facilitate cutting. Jaw member 1120 may also beconfigured to include a different geometrical configuration from jawmember 1110 to produce a particular cutting effect. Moreover, aninsulator (not shown) may be disposed between one or both of thepartially conductive materials 1113 and 1123 and its respective sealingsurface to reduce electrical conduction or heat transfer between oracross these elements.

FIG. 4F shows a similar electrode assembly 1205 having sealing surfaces1212 a and 1212 b which are separated by a partially conductive material1213 and wherein the partially conductive material 1213 is generallyrounded but does not extend beyond the sealing surfaces 1212 a and 1212b. The partially conductive material 1213 is preferably made from amaterial such as those identified above which produces an area of highpower density at the apex 1251 to cut tissue disposed thereunder duringthe cutting phase. Again, the opposite jaw member (not shown) may beconfigured as a mirror image of the jaw member 1210 or may include adifferent geometrical configuration.

FIG. 4G shows another geometric configuration of a jaw member 1310 whichincludes sealing surfaces 1312 a and 1312 b separated by a partiallyconductive material 1313 wherein the partially conductive material isset back between the sealing surface 1312 a and 1312 b to define arecess 1349 therein. FIG. 4H shows yet another geometric configurationof a jaw member 1410 which forms part of an electrode assembly 1405 andwhich includes sealing surface 1412 and a partially conductive material1413. As can be appreciated this particular arrangement does not includea second sealing surface on the upper jaw member 1410 but instead thepartially conductive material 1413 includes a notch-like recess 1449defined therein which has a cutting tip 1451 which extends beyondsealing surface 1412. It is envisioned that the cutting tip 1451 extendsbeyond the sealing surface 1412 enough to both maintain the necessarygap distance during the sealing phase and to eventually facilitatetissue cutting during the cutting phase by producing an area of highpower density at the tip 1451. Again, the opposite jaw member (notshown) may be configured as a mirror image of the jaw member 1410 or mayinclude a different geometrical configuration.

FIG. 4I includes yet another geometric configuration of the upper jawmember 1510 which forms part of an electrode assembly 1505 and whichincludes sealing surfaces 1512 a and 1512 b which are separated by aninsulator 1513. The insulator 1513 includes a generallyrectilinear-shaped semi-conductive cutting element 1527 disposed thereinwhich extends beyond the sealing surfaces 1512 a and 1512 b. As can beappreciated, during the cutting phase, the semi-conductive cuttingelement 1527 is energized by a first potential “+” and the sealingplates 1512 a, 1512 b is energized to a second potential “−”. Theinsulator 1513 isolates the potentials between the partially conductivematerial 1527 and the sealing surfaces 1512 a and 1512 b duringactivation.

FIG. 4J shows still yet another geometric configuration showing a jawmember 1610 for an electrode assembly 1605 which is similar to FIG. 4Cabove which includes a C-shaped sealing plate 1612 having a recess 1621defined therein for housing an insulator 1613. The insulator 1613includes a semi-conductive cutting element 1627 housed therein forcutting tissue. During the cutting phase, the semi-conductive cuttingelement 1627 is energized to a first potential “+” and the sealing plate1612 is energized to a second potential “−” to effect tissue cutting.Again, the lower or second jaw member (not shown) may include the samegeometric configuration to enhance the cutting process.

FIG. 5 shows a schematically-illustrated example of electrical circuitryfor an electrode assembly 1905 which may be utilized to initially sealtissue between the sealing plates and subsequently cut tissue once thetissue seal(s) are formed. More particularly, jaw member 1910 includesinsulative housing 1916 which is dimensioned to house conductive sealingplates 1912 a and 1912 b with an insulator or partially conductivematerial 1913 disposed therebetween. Insulator/partially conductivematerial 1913 includes a recess 1921 defined therein which isdimensioned to retain a generally triangularly-shaped cutting element1927 which extends beyond sealing surfaces 1912 a and 1912 b. Jaw member1920 includes an outer insulative housing 1926 which is dimensioned tohouse electrically conductive sealing surface 1922. Sealing surface 1922includes a recess 1933 defined therein which generally compliments thecross sectional profile of cutting element 1927. Preferably, the cuttingelement 1927 is dimensioned slightly larger than the recess 1933 suchthat a gap is formed when the jaw members are closed about tissue, thegap being within the above-identified working range.

During sealing (Vseal), the sealing plates 1912 a and 1912 b areenergized to a first potential “+₁” and sealing plate 1922 is energizedto a second potential “−”. The cutting element is not energized. Sincethe insulator or semi-conductor does not conduct energy as well as theconductive sealing plates 1912 a and 1912 b, the first potential is noteffectively or efficiently transferred to the cutting element 1927 andthe tissue is not necessarily heated or damaged during the sealingphase. During the sealing phase energy is transferred from the sealingplates 1912 a and 1912 b through the tissue and to the return electrode1922 (Vreturn). It is believed that even if some energy is effectivelytransferred to the cutting element 1927 during the sealing phase, itwill simply preheat or pre-treat the tissue prior to separation andshould not effect the cutting phase. During the sealing phase, thecutting element 1927 mainly acts as a stop member for creating andmaintaining a gap between the opposing sealing surfaces 1912 a, 1912 band 1922.

During the cutting phase (Vcut), a first potential “+₂” is supplied tothe cutting element 1927 and a second potential “−” is supplied to thesealing surface 1922. The electrical parameters (power, current,waveform, etc.) associated with this phase may be the same or differentthan the potentials used for the sealing phase. It is believed thatsimilar first and second potentials may be utilized since differentcomponents with varying geometries are being energized which bythemselves are envisioned to create different electrical effects. As canbe appreciated, during the cutting phase energy is transferred from thecutting element 1927 through the tissue and to the return electrode 1922(Vreturn). It is believed that even if some energy is transferred to thesealing plates 1912 a and 1912 b during the cutting phase through theinsulator/semi-conductor 1913, it will not detrimentally effect thealready formed tissue seals. Moreover, it is believed that one or moresensors (not shown), computer algorithms and/or feedback controlsassociated with the generator or internally disposed within the forcepsmay be employed to prevent overheating of the tissue during the sealingand cutting phases.

FIGS. 6A-6D show additional embodiments of jaw members having variouselectrode assemblies which may be utilized for sealing and cuttingtissue disposed between the jaw members. For example, FIG. 6A shows afirst or upper jaw member 2010 for use with an electrode assembly 2005which includes an electrically conductive sealing surface 2012 having arecess 2021 defined therein dimensioned to house an insulator 2013. Theinsulator also includes a notch 2049 disposed therein which partiallyhouses a generally rectilinearly-shaped cutting electrode 2027.Electrode 2027 is preferably recessed or set back within notch 2049. Jawmember 2020 includes an electrically conductive sealing surface 2022which is disposed in substantial vertical registration with opposingsealing surface 2012. Sealing surface 2022 includes a generallyrectilinearly-shaped insulator 2023 which extends towards jaw member2010 and is configured to abut electrode 2027 when the jaw members 2010and 2020 are moved into the closed position about tissue. As can beappreciated, the insulator 2023 acts as a stop member and creates a gapdistance within the above working range during the sealing process. Inaddition, the two insulators 2013 and 2023 insulate the upper jaw member2010 during the cutting phase and generally direct the cutting currentfrom the cutting element 2027 in an intense fashion towards the returnelectrode 2022 (Vreturn) to effectively cut tissue.

FIG. 6B shows yet another embodiment of an electrode assembly 2105disposed on jaw members 2110 and 2120. More particularly, jaw members2110 and 2120 include electrically conductive sealing surfaces 2112 and2122, respectively, disposed in general vertical registration relativeto one another and which are configured to seal tissue during thesealing phase. Much like the embodiment described above with respect toFIG. 6A, jaw member 2110 includes a recess 2121 defined thereindimensioned to house an insulator 2113. Jaw member 2120 includes anelectrically conductive sealing surface 2122 which is disposed insubstantial vertical registration with opposing sealing surface 2112.Jaw member 2120 includes an insulator 2123 disposed therein which isdisposed opposite recess 2121.

The insulator 2113 also includes a T-shaped cutting element 2127 housedtherein which defines two notches 2149 a and 2149 b on either side of aleg or extension 2127 a which extends towards jaw member 2120. Thecutting element 2127 is preferably made from a relatively low conductivematerial and includes an area of highly conductive material 2139disposed at the distal end of the leg 2127 a. The highly conductivematerial 2139 is disposed in vertical registration with the insulator2123 disposed in jaw member 2120. During activation of the cuttingphase, it is believed that the highly conductive material 2139 willfocus the cutting current in an intense fashion towards the returnelectrode 2122 (Vreturn) to cut the tissue disposed between jaw members2110 and 2120.

FIG. 6C shows yet another set of jaw members 2210 and 2220 with anelectrode assembly 2205 disposed thereon for sealing and cutting tissue.More particularly, jaw member 2210 includes an electrically conductivesealing surface 2212 having a recessed portion 2221 disposed therein forhousing an insulator 2213 which, in turn, houses a generally V-shapedcutting element 2227 therein. Jaw member 2220 includes an electricallyconductive sealing surface 2222 which opposes sealing surface 2212 onjaw member 2210. During the sealing phase, sealing surfaces 2212 and2222 conduct electrosurgical energy through tissue held therebetween toeffect a tissue seal. V-shaped cutting element 2227 acts as a stopmember during the sealing phase.

During the cutting phase, V-shaped cutting element 2227 pinches thetissue held between the jaw members 2210 and 2220 and when activateddirects electrosurgical energy through the tissue in an intense fashionaround insulator 2213 and towards sealing surface 2212. Jaw member 2220remains neutral during the cutting phase and is not believed tosignificantly alter the direction of the electrical path to adverselyeffect the cutting process.

FIG. 6D shows yet another embodiment of jaw members 2310 and 2320 havingan alternative electrode assembly 2305 for sealing and cutting tissue.More particularly, the electrode assembly 2305 is similar to theelectrode configuration of the embodiment described with respect to FIG.6C with the exception that the lower jaw member 2320 includes aninsulator 2323 disposed in vertical registration with the cuttingelement 2327 disposed within the recess 2321 of the upper jaw member2310. In this instance, the cutting element 2327 is dimensioned to bewider than the insulator 2323 such that the rear portions of theV-shaped cutting element extend laterally beyond the insulator 2323 whenthe jaw members 2310 and 2320 are disposed in the closed position. Inother words the, cutting element 2327 includes an overhang portion whichis disposed in opposing vertical registration with the return electrode2322. The insulator 2313 disposed within the recess 2321 of the upperjaw member 2310 helps to direct the electrosurgical energy towards thereturn electrode 2322 during cutting and reduces stray currents toadjacent tissue structures.

During the sealing phase, sealing surfaces 2312 and 2322 conductelectrosurgical energy through tissue held therebetween to effect twotissues seals on opposite sides of insulator 2313. V-shaped cuttingelement 2327 acts as a stop member during the sealing phase. During thecutting phase, jaw member 2310 is neutralized and cutting element 2327is energized such that electrosurgical energy is directed from thecutting element 2327 through tissue held between the jaw members 2310and 2320 and to the return electrode 2322 (Vreturn). It is believed thatthe V-shaped cutting element 2327 will direct energy to the returnelectrode 2322 in an intense fashion around insulator 2323 and towardssealing surface 2212 to effectively cut the tissue between the alreadyformed tissue seals.

FIGS. 7A-7D show various geometric configurations of cutting elementsand insulators for use with the electrode assemblies of forceps 10, 100according to the present disclosure. For example, FIG. 7A shows oneembodiment wherein one of the electrode assemblies 2405 includes jawmembers 2420 having first and second electrically conductive sealingsurfaces 2422 a and 2422 b which are of opposite electrical potentialsand which are separated by a trapeziodally-shaped insulator 2423 whichextends beyond each respective sealing surface 2422 a and 2422 b. As canbe appreciated the particular shape of the frustoconically-shapedinsulator 2423 forms two recessed portions 2459 a and 2459 b between thesealing surfaces 2422 a, 2422 b and the insulator 2423 which isenvisioned to both pinch the tissue between the insulator 2423 and theopposing surface (e.g., another insulator or conductive surface) andcontrol the electrosurgical energy during activation to facilitatecutting.

FIG. 7B shows another similar embodiment which includes afrustoconcically-shaped insulator 2523 which does not extend beyond thesealing surfaces 2522 a and 2522 b but is actually slightly set backfrom the sealing surfaces 2522 a and 2522 b. Again, the particular shapeof the trapeziodally-shaped insulator 2523 forms two recessed portions2559 a and 2559 b between the sealing surfaces 2522 a, 2522 b and theinsulator 2523 which is envisioned to control the electrosurgical energyduring activation to enhance the cutting process.

FIG. 7C shows another geometrical configuration of an electrode assembly2605 which includes one active electrically conductive surface 2622 aand one neutral electrically conductive surface 2622 b during thecutting phase. A cutting element 2627 is disposed between the twosurfaces 2622 a and 2622 b and is separated from the surfaces by aninsulator 2623 which is recessed between the two surfaces 2622 a and2622 b to form notches or set back areas 2659 a and 2659 b. The cuttingelement 2627 is designed with a smaller radius of curvature than theactive electrode 2622 a such that during the cutting phase,electrosurgical energy is intensified to create a sufficient powerdensity to effectively cut tissue proximate the cutting element 2627.

FIG. 7D shows another geometric configuration of an electrode assembly2705 similar to the embodiment shown in FIG. 7C above wherein theinsulator 2723 is configured to be generally flush with the surfaces2722 a and 2722 b. The cutting element 2727 is disposed within theinsulator 2723 and extends from both the insulator 2723 and the surfaces2722 a and 2722 b towards an opposing surface on the other jaw member(not shown). It is believed that the shape of the insulator 2723 willdirect intensified electrosurgical current between the cutting element2727 and the active conductive surface 2722 a.

FIG. 7E shows yet another electrode assembly 2805 having a jaw member2820 with a geometric configuration similar FIG. 7C above wherein theinsulator 2823 is recessed between the two sealing surfaces 2822 a and2822 b. A generally rounded cutting element 2827 is disposed within theinsulator 2823. The cutting element 2827 includes a larger radius ofcurvature than the radius of curvature of the active surface 2822 a suchthat during the cutting phase, electrosurgical energy is intensified toeffectively cut tissue proximate the cutting element 2827.

As can be appreciated, the various geometrical configurations andelectrical arrangements of the aforementioned electrode assemblies allowthe surgeon to initially activate the two opposing electricallyconductive tissue contacting surfaces and seal the tissue and,subsequently, selectively and independently activate the cutting elementand one or more tissue contacting surfaces to cut the tissue utilizingthe various above-described and shown electrode assembly configurations.Hence, the tissue is initially sealed and thereafter cut withoutre-grasping the tissue.

However, it is envisioned that the cutting element and one or moretissue contacting surfaces may also be activated to simply cuttissue/vessels without initially sealing. For example, the jaw membersmay be positioned about tissue and the cutting element may beselectively activated to separate or simply coagulate tissue. This typeof alternative embodiment may be particularly useful during certainendoscopic procedures wherein an electrosurgical pencil is typicallyintroduced to coagulate and/or dissect tissue during the operatingprocedure.

A switch 70 may be employed to allow the surgeon to selectively activateone or more tissue contacting surfaces or the cutting elementindependently of one another. As can be appreciated, this allows thesurgeon to initially seal tissue and then activate the cutting elementby simply turning the switch. Rocker switches, toggle switches, flipswitches, dials, etc. are types of switches which can be commonlyemployed to accomplish this purpose. It is also envisioned that theswitch may cooperate with the smart sensor (or smart circuit, computer,feedback loop, etc.) which automatically triggers the switch to changebetween the “sealing” mode and the “cutting” mode upon the satisfactionof a particular parameter. For example, the smart sensor may include afeedback loop which indicates when a tissue seal is complete based uponone or more of the following parameters: tissue temperature, tissueimpedance at the seal, change in impedance of the tissue over timeand/or changes in the power or current applied to the tissue over time.An audible or visual feedback monitor may be employed to conveyinformation to the surgeon regarding the overall seal quality or thecompletion of an effective tissue seal. A separate lead may be connectedbetween the smart sensor and the generator for visual and/or audiblefeedback purposes.

Preferably, the generator 500 delivers energy to the tissue in apulse-like waveform. It has been determined that delivering the energyin pulses increases the amount of sealing energy which can beeffectively delivered to the tissue and reduces unwanted tissue effectssuch as charring. Moreover, the feedback loop of the smart sensor can beconfigured to automatically measure various tissue parameters duringsealing (i.e., tissue temperature, tissue impedance, current through thetissue) and automatically adjust the energy intensity and number ofpulses as needed to reduce various tissue effects such as charring andthermal spread.

It has also been determined that RF pulsing may be used to moreeffectively cut tissue. For example, an initial pulse from the cuttingelement through the tissue (or the tissue contacting surfaces throughthe tissue) may be delivered to provide feedback to the smart sensor forselection of the ideal number of subsequent pulses and subsequent pulseintensity to effectively and consistently cut the amount or type oftissue with minimal effect on the tissue seal. If the energy is notpulsed, the tissue may not initially cut but desiccate since tissueimpedance remains high during the initial stages of cutting. Byproviding the energy in short, high energy pulses, it has been foundthat the tissue is more likely to cut.

Alternatively, a switch may be configured to activate based upon adesired cutting parameter and/or after an effective seal is created orhas been verified. For example, after effectively sealing the tissue,the cutting element may be automatically activated based upon a desiredend tissue thickness at the seal.

As mentioned in many of the above embodiments, upon compression of thetissue, the cutting element acts as a stop member and creates a gap “G”between the opposing conductive tissue contacting surfaces. Preferablyand particularly with respect to vessel sealing, the gap distance is inthe range of about 0.001 to about 0.006 inches. As mentioned above,controlling both the gap distance “G” and clamping pressure betweenconductive surfaces are two important mechanical parameters which needto be properly controlled to assure a consistent and effective tissueseal. The surgeon activates the generator to transmit electrosurgicalenergy to the tissue contacting surfaces and through the tissue toeffect a seal. As a result of the unique combination of the clampingpressure, gap distance “G” and electrosurgical energy, the tissuecollagen melts into a fused mass with limited demarcation betweenopposing vessel walls.

Once sealed, the surgeon activates the cutting element to cut thetissue. As mentioned above, the surgeon does not necessarily need tore-grasp the tissue to cut, i.e., the cutting element is alreadypositioned proximate the ideal, center cutting line of the seal. Duringthe cutting phase, highly concentrated electrosurgical energy travelsfrom the cutting element through the tissue to cut the tissue into twodistinct halves. As mentioned above, the number of pulses required toeffectively cut the tissue and the intensity of the cutting energy maybe determined by measuring the seal thickness and/or tissue impedanceand/or based upon an initial calibrating energy pulse which measuressimilar parameters. A smart sensor (not shown) or feedback loop may beemployed for this purpose.

As can be appreciated, the forceps may be configured to automaticallycut the tissue once sealed or the instrument may be configured to permitthe surgeon to selectively divide the tissue once sealed. Moreover, itis envisioned that an audible or visual indicator (not shown) may betriggered by a sensor (not shown) to alert the surgeon when an effectiveseal has been created. The sensor may, for example, determine if a sealis complete by measuring one of tissue impedance, tissue opaquenessand/or tissue temperature. Commonly-owned U.S. application Ser. No.10/427,832 which is hereby incorporated by reference herein describesseveral electrical systems which may be employed to provide positivefeedback to the surgeon to determine tissue parameters during and aftersealing and to determine the overall effectiveness of the tissue seal.

Preferably, the electrosurgical intensity from each of the electricallyconductive surfaces and cutting elements is selectively or automaticallycontrollable to assure consistent and accurate cutting along thecenterline of the tissue in view of the inherent variations in tissuetype and/or tissue thickness. Moreover, it is contemplated that theentire surgical process may be automatically controlled such that afterthe tissue is initially grasped the surgeon may simply activate theforceps to seal and subsequently cut tissue. In this instance, thegenerator may be configured to communicate with one or more sensors (notshown) to provide positive feedback to the generator during both thesealing and cutting processes to insure accurate and consistent sealingand division of tissue. As mentioned above, commonly-owned U.S. patentapplication Ser. No. 10/427,832 discloses a variety of feedbackmechanisms which may be employed for this purpose.

From the foregoing and with reference to the various figure drawings,those skilled in the art will appreciate that certain modifications canalso be made to the present disclosure without departing from the scopeof the present disclosure. For example, it is contemplated that cuttingelement may be dimensioned as a cutting wire which is selectivelyactivatable by the surgeon to divide the tissue after sealing. Moreparticularly, a wire is mounted within the insulator between the jawmembers and is selectively energizable upon activation of the switch.

The forceps may be designed such that it is fully or partiallydisposable depending upon a particular purpose or to achieve aparticular result. For example, the electrode assembly may beselectively and releasably engageable with the distal end of the shaftand/or the proximal end of shaft may be selectively and releasablyengageable with the housing and the handle assembly. In either of thesetwo instances, the forceps would be considered “partially disposable” or“reposable”, i.e., a new or different electrode assembly (or electrodeassembly and shaft) selectively replaces the old electrode assembly asneeded.

It is envisioned that the electrode assembly could be selectivelydetachable (i.e., reposable) from the shaft depending upon a particularpurpose, e.g., it is contemplated that specific forceps could beconfigured for different tissue types or thicknesses. Moreover, it isenvisioned that a reusable forceps could be sold as a kit havingdifferent electrodes assemblies for different tissue types. The surgeonsimply selects the appropriate electrode assembly for a particulartissue type.

It is also envisioned that the forceps could include a mechanical orelectrical lockout mechanism which prevents the sealing surfaces and/orthe cutting element from being unintentionally activated when the jawmembers are disposed in the open configuration.

Although the subject forceps and electrode assemblies have beendescribed with respect to preferred embodiments, it will be readilyapparent to those having ordinary skill in the art to which itappertains that changes and modifications may be made thereto withoutdeparting from the spirit or scope of the subject devices. For example,although the specification and drawing disclose that the electricallyconductive surfaces may be employed to initially seal tissue prior toelectrically cutting tissue in one of the many ways described herein, itis also envisioned that the electrically conductive surfaces may beconfigured and electrically designed to perform any known bipolar ormonopolar function such as electrocautery, hemostasis, and/ordesiccation utilizing one or both jaw members to treat the tissue.Moreover, the jaw members in their presently described and illustratedformation may be energized to simply cut tissue without initiallysealing tissue which may prove beneficial during particular surgicalprocedures. Moreover, it is contemplated that the various geometries ofthe jaw members, cutting elements, insulators and semi-conductivematerials and the various electrical configurations associated therewithmay be utilized for other surgical instrumentation depending upon aparticular purpose, e.g., cutting instruments, coagulation instruments,electrosurgical scissors, etc.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of preferred embodiments. Those skilled in the art willenvision other modifications within the scope and spirit of the claimsappended hereto.

1. An end effector assembly for use with an instrument for sealing andcutting tissue, the end effector assembly comprising: a pair of opposingfirst and second jaw members at least one of which being movablerelative to the other from a first position wherein the jaw members aredisposed in spaced relation relative to one another to a second positionwherein the jaw members cooperate to grasp tissue therebetween; each jawmember including a pair of spaced apart, electrically conductive tissuesealing surfaces extending along a length thereof, each tissue sealingsurface adapted to connect to a source of electrosurgical energy suchthat the tissue sealing surfaces are capable of conductingelectrosurgical energy through tissue held therebetween to effect atissue seal; a partially conductive material disposed within each pairof electrically conductive tissue sealing surfaces; the first jaw memberincluding an electrically conductive cutting element disposed within thepartially conductive material of the first jaw member, the electricallyconductive cutting element disposed in general vertical registration tothe partially conductive material on the second jaw member; wherein thecutting element is configured to create a gap between the pairs ofelectrically conductive tissue sealing surfaces when the jaw members arein the second position; the cutting element being inactive during a thesealing process and the pair of spaced apart, electrically conductivetissue sealing surfaces on the first jaw member being energized to adifferent potential from the corresponding pair of spaced apartelectrically conductive tissue sealing surfaces on the second jaw membersuch that electrosurgical energy can be transferred through the tissueto effect the tissue seal; and the cutting element being energized to afirst potential during a cutting process and at least one electricallyconductive tissue sealing surface on the first jaw member and at leastone electrically conductive tissue sealing surface on the second jawmember being energized to a different potential such thatelectrosurgical energy can be transferred through the tissue to effect atissue cut.
 2. An end effector assembly according to claim 1 wherein thepotential of the at least one electrically conductive tissue sealingsurface of the first jaw member and the potential of the cutting elementare independently activatable by the surgeon.
 3. An end effectorassembly according to claim 1 wherein the electrical potential of thecutting element and the electrical potential of the at least oneelectrically conductive tissue sealing surface are automaticallyconfigured for the cutting process when the surgeon selectivelyactivates a trigger.
 4. An end effector assembly according to claim 1wherein the cutting element is substantially dull and capable of cuttingtissue only through electrosurgical activation.
 5. An end effectorassembly according to claim 1 further comprising a smart sensor fordetermining seal quality prior to the cutting process.
 6. An endeffector assembly according to claim 5 wherein the smart sensor includesone of an audible or visual indicator for indicating seal quality.
 7. Anend effector assembly according to claim 5 wherein the smart sensor isoperable to automatically switch electrosurgical energy to the cuttingelement once the tissue is sealed.
 8. An end effector assembly accordingto claim 1 further comprising a first switch for energizing theelectrically conductive tissue sealing surfaces to effect tissue sealingand a trigger for energizing the cutting element and at least one of theelectrically conductive tissue sealing surfaces to effect tissuecutting.
 9. An end effector assembly according to claim 1 wherein atleast one of the partially conductive material is configured to at leastpartially extend to a position that is at least substantially flush withthe cutting element.
 10. An end effector assembly according to claim 1further comprising a second electrically conductive cutting elementdisposed within the partially conductive material of the second jawmember, the second electrically conductive cutting element opposing thefirst electrically conductive cutting element.
 11. An end effectorassembly according to claim 10 wherein the first and second electricallyconductive cutting elements, when disposed on opposite sides of tissue,form the gap distance between the pairs of electrically conductivetissue sealing surfaces when the jaw members are disposed in the secondposition.
 12. An end effector assembly for use with an instrument forsealing and cutting vessels and/or tissue, the end effector assemblycomprising: a pair of opposing first and second jaw members at least oneof which being movable relative to the other from a first positionwherein the jaw members are disposed in spaced relation relative to oneanother to a second position wherein the jaw members cooperate to grasptissue therebetween; each jaw member including a pair of spaced apart,electrically conductive tissue sealing surfaces extending along a lengththereof, each tissue sealing surface adapted to connect to a source ofelectrosurgical energy such that the tissue sealing surfaces are capableof conducting electrosurgical energy through tissue held therebetween toeffect a tissue seal; a partially conductive material disposed betweeneach pair of electrically conductive tissue sealing surfaces; the firstjaw member including an electrically conductive cutting element disposedwithin the partially conductive material of the first jaw member, theelectrically conductive cutting element disposed in general verticalregistration to the partially conductive material of the second jawmember; at least one stop member operatively associated with one of thefirst and second jaw members being dimensioned to create a gap betweenthe pairs of electrically conductive tissue sealing surfaces when thejaw members are in the second position; the cutting element beinginactive during a sealing process and the pair of spaced apartelectrically conductive tissue sealing surfaces on the first jaw memberbeing energized to a different potential from the corresponding pair ofspaced apart electrically conductive tissue sealing surfaces on thesecond jaw member such that electrosurgical energy can be transferredthrough the tissue to effect the tissue seal; and the cutting elementbeing energized to a first potential during a cutting process and atleast one electrically conductive tissue sealing surface on the firstjaw member and at least one electrically conductive tissue sealingsurface on the second jaw member being energized to a differentpotential such that electrosurgical energy can be transferred throughthe tissue to effect a tissue cut.